At National Institute of Radiological Sciences (NIRS), a total of 48 patients including 32 GBM and 16 anaplastic astrocytoma were treated in the phase I/II dose escalation study [9] C-ion RT followed by photon radiotherapy was accomplished via dose escalation up to the fifth level (16.8, 18.4, 20.0, 22.4, and 24.8 GyE), with all patients receiving treatment as scheduled.

The median survival time (MST) for the 32 GBM patients was 17 months. The patients were subdivided into three groups according to the carbon ion dose: the low-dose group (16.8 GyE), the middle-dose group (18.4–22.4 GyE), and the high-dose group (24.8 GyE). In the 32 patients with GBM, the MST was 7, 19, and 26 months for the low-dose, moderate-dose, and high-dose groups, respectively. Univariate analysis of the 32 patients with GBM revealed that only the carbon ion dose showed statistical significance. Non-hematological severe adverse effects were few. Maximum acute reaction of the skin was grade 2 and that of the brain was grade 1. In late morbidity of the brain, four patients had grade 2 reaction, requiring steroid administration. However, no grade 3/4 reactions occurred.